Pleuromamma quadrungulata   (Dahl F,  1893) (Copepod)
Organism information awaits expert curation
Taxonomy
Kingdom:Animalia
Phylum:Arthropoda
Class: Maxillopoda
Order:Calanoida
Family:Metridinidae

Description
Size (female): length 3.0-3.62 mm.

The proportional lengths of the cephalothorax and abdomen are as 66 to 31; so that the abdomen is contained 2.1 times in the length of the anterior region of the body.The forehead terminates in a rostrum that has swollen base and consists of a pair of slender spines. Thoracic segments 4 and 5 are fused together. The posterior margin of the thorax is rounded.

The abdomen consists of three free segments.The third free segment (anal) is produced laterally in short rounded processes, directed outwards and backwards. The furcal rami are symmetrical; the inner margins are clad with hair and there are five furcal setae, of which the 5th or outer seta is inserted into the middle of the outer margin of the ramus, while the remainder are terminal.

The 1st antenna reaches to the middle of the furcal ramus. Segments 7, 8 and 9 are fused together and segment 10 is partially fused to segment 9; segments 12 and 13 are also fused. Segment 1 bears two claw-like spines that are recurved towards the proximal end. Of these one is situated near the base and the other distally. There are three cutaneous pores near the anterior margin of the segment. On being at the base of the proximal spine, another at the base of the distal spine and the third approximately mid-way between. Segments 2 and 4 each carry a single recurved spine and there is a single pore on segment 2 near the base of the spine. Segment 3 is devoid of a spine but segments 5 and 6 each have a small spinous process on their anterior margin.

In the 1st swimming leg basal 1 bears a single internal seta and there are a few hairs on the inner margin; basal 2 bears the usual S-shaped internal seta and there is a tuft of hairs distally on the inner margin. Each ramus consists of three segments. Exopod 1 and 2 each bear a single seta and an internal marginal spine. Exopod 3 bears two long marginal spines on its outer border and four setae on its inner margin. All the marginal spines are delicate and seta-like. The end-spine is long and does not appear to be serrated. Endopod 1 bears a single seta internally and is armed with a row of needle-like spines that runs across its anterior aspect. Endopod 2 has a fringed outer margin and bears two setae. Endopod 3 bears five setae, of which the outer is small. There is a pointed process on the posterior aspect of the 2nd basal segment.

In the 2nd swimming leg basal 1 bears an inner seta but no marginal spines; there are three cutaneous pores on its anterior surface. Basal 2 bears a group of scattered, very minute spinules on its outer surface. In the 1st segment of the exopod there is a stout spinous projection near the base on the anterior aspect and running upwards from this is a row of small triangular spines; the segment bears a single marginal spine that is leaf-like, and a single small inner seta. Exopod 2 also bears a single leaf-like marginal spine and a stout inner seta and, in addition, both margins are fringed with hairs, which are minute on the outer border but long on the inner. Exopod 3 has three leaf-like marginal spines and the outer border is fringed with hair; the inner margin carries five setae. The end-spine is finely serrated. The 1st segment of the endopod bears the hook-like recurved spines that are characteristic of this genus; but the distal spine in this species appears to be single; the outer margin is fringed with ahir. The endopod consists of three free segments and reaches as far as the joint between the 2nd and 3rd segments of the exopod. Exopod 2 possesses two setae on its inner margin; the outer margin bears a spinous projection at its distal inner angle and is fringed with hair. Exopod 3 carries eight setae. Numerous cutaneous pores are scattered over the whole limb. On the 1st basal segment there are three pores opening on the anterior aspect; in the 2nd basal segment there is a single pore near the distal external angle. Three pores open to the exterior on the outer margin near the base of the external spine. On exopod 2 one pore opens on the outer margin about the middle of the length of the segment and a second near the base of the marginal spine. In exopod 3 two pores open near the margin between the proximal end of the segment and the 1st marginal spine, a second opens near the base of the 2nd and 3rd marginal spine.

In the 3rd swimming leg basal 1 bears a single inner seta and there are a few scattered short needle-like spines on the outer aspect of the segment. Basal 2 bears no spine or seta. The 1st segment of the exopod is characterized by a long extension of its outer distal angle at the apex of which the leaf-like marginal spine is situated; this process is separated from the rest of the segment by a deep notch; a single seta arises from the inner border. Exopod 2 bears a single leaf-like marginal spine and a single inner seta; the outer margin is crest-like and has an angular outline. Exopod 3 bears three leaf-like marginal spines and five setae. The end-spine is comparatively short and is about equal in length to the interval between the 2nd and 3rd marginal spines. Endopod 1 bears a single inner seta. Endopod 2 bears two setae and endopod 3 has six. The outer margins of the 1st and 2nd segments are fringed with hair. Two pores open on the 1st basal segment near the distal outer angle; on the 2nd basal segment there is a single pore near the articulation of the exopod. In the 1st segment of the exopod five pores open on the outer margin; two about the middle of the length of the segment; one about the middle of the length of the process and two near the base of the marginal spine. Two pores open near the outer margin of the second segment and two on the proximal side of each of the three marginal spines on the 3rd segment.

The 4th swimming leg closely resembles the 3rd but the outer part of the 1st segment of the exopod is not produced. The 5th pair of legs is symmetrical and each consists of a basal segment and three free segments. The 1st free segment bears a long seta on its outer margin and a single pore opens near its articulation. The 2nd free segment has a stout spine at its distal outer angle and the inner margin possesses a row of long hairs. The 3rd free segment bears three setae that arise from its distal aspect; of these setae the outermost is comparatively short and delicate and the inner is stout and is equal in length to the whole free portion of the limb.



Synonym (s)
Pleuromamma quadrungulata Dahl, 1893
Pleuromamma quadrangulata Wolfenden, 1911

Common Name (s)
Economic Importance and Threats

Ecology

Biogeography


• Bay of Bengal (Lat: 7.35) (Long: 85.12) INDIA (Record: 21/10/1911)
• Bay of Bengal (Lat: 7.61) (Long: 84.31) INDIA (Record: 21/04/1912)
• Indian Ocean (Lat: 5.93) (Long: 76.36) (Record: 21/04/1924)

Literature Source(s)
  • Sewell, RBS (1999) The copepoda of Indian seas Biotech Books, Delhi, India 407 pp Available at - NIO, Goa
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at - http://www.marinespecies.org

Page last updated on:2011-03-16

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